Hydraulic transmission



NOV. 1, B BURHOP HYDRAULIC TRANSMI S S ION Filed March 50, 1958INVENTOR. @Mafi/ ATTORNEY Patented Nov. 1, 1938 UNITED STATES PATENTOFFICE '10 Claims.

My present invention relates to improvements in the art of transferringpower from one member to another, and relates more specifically toimprovements in the construction and operation of mechanism fortransmitting motion from a driving element to a driven element at anydesired speed.

Generally defined, an object of my invention is to provide an improvedhydraulic transmission mechanism which is simple and compact inconstruction, and which is moreover highly eflicient in operation.

It has heretofore been proposed to provide a hydraulic transmissionconsisting of two or more reciprocating pump units interposed betweenrotary alined driving and driven shafts, for the purpose of transferringmotion at variable speed from one of the shafts ,to the other. In one ofthese prior transmission mechanisms which was especially contemplatedfor use in automobile propulsion, it was proposed to obtain the desiredspeed variation, by providing each pump unit with a pair ofsimultaneously reciprocable pistons having a body of oil or other liquidconfined therebetween, and also having a stationary diaphragm withadjustable by-pass openings therein located between the alined andinterconnected pistons and within the body of oil. By correspondinglyvarying the eifective area of the by-pass openings of all of thediaphragms of the several pump units, it was contemplated to vary thespeed of rotation of the driven shaft, the variation in velocity of flowof the liquid through the diaphragm, openings being utilized to effectthe speed changes. Other types of these hydraulic transmissions havealso been proposed, and while the theory of operation is infallible,none of these prior mechanisms have proven commercially practicable fornumerous reasons, such as undue complications in structure, inaccuracyin transmission due to inability to prevent excessive escape ofactuating liquid and slippage thereof, excessive bulk of the assemblagesand heating of the liquid, and extreme difficulty in operation.

The present invention therefore contemplates provision of an improvedhydraulic variable speed transmission of the above mentioned generaltype, which is also especially adapted for vehicle propulsion or thelike, and wherein the deficiencies of the prior devices are obviated.

In accordance with my present improvement, I provide two or moreindependent pump units each having a cylinder and a single pistonprovided with an improved balanced by-pass valve, all of the valvesbeing accurately, conveniently and simultaneously controllable to secureany desired speed between zero and the speed of rotation of the drivingmember. The improved assemblage is relatively light and compact in orderto eliminate undesirable flywheel effect, but is extremely durable andrelatively simple and easy to construct and assemble. The various partsof my improved device are also easily accessible, and the actuatingliquid cannot become excessively heated. I have also provided improvedmeans for initially filling the pump chambers with liquid, and forsubsequently compensating for possible loss of liquid due to leakage;and I have moreover provided a mechanism wherein undesirable slippage iseliminated and accurate transmission at any desired speed is madepossible and practicable for various purposes.

A clear conception of an embodiment of my invention, and of the mode ofconstructing and of utilizing variable speed hydraulic transmissionsbuilt in accordancewith the improvement, may be had by referring to thedrawing accompanying and forming a part of this specification whereinlike reference characters designate the same or similar parts in thevarious views.

Fig. 1 is a part sectional top view of my improved hydraulictransmission mechanism;

Fig. 2 is a part sectional side view of the assemblage, showing theby-pass valve Wide open; and

Fig. 3 is a fragmentary sectional side view of one of the pump pistonswith the by-pass valve completel closed.

While I have shown only one form of the improved hydraulic transmissionmechanism here-' in which is especially adapted for the propulsion ofvehicles such as automobiles, it is not the intent to therebyunnecessarily restrict the scope or utility.

Referring to the drawing, the improved transmission assemblage. showntherei-n comprises in general a driving member or shaft 6; a drivenmember or shaft 1 disposed in approximately axial alinement with theshaft 6; a pump casing 8 secured to and revolvable with the shaft 1 andhaving therein two parallel cylinder bores 9; a piston l reciprocablewithin each of the bores 9 and each having an adjustable butterflybypass valve I l therein; a frame consisting of interconnected sectionsi2, It revolvable with and nected to the pump casing 8 and beingjournalled for relative rotation upon the driving shaft 6; piston rodsI4 slidable within the frame section l2 and having cross-heads lcoacting with par allel guides l6 confined within this section I2:

crank shafts I'I, I8 rotatably journalled in the frame section I3 andhaving staggered cranks I9, 20 connected to the respective cross-headsI5 by means of connecting rods 2|; bevel pinions 22, 23 securedrespectively to the crank shafts II, I8; a bevel gear 24 secured to theend of the shaft Ii within the frame section I3 and meshing with thepinions 22, 23 so as to cause the latter to revolve in oppositedirections; and mechanism for effecting adjustment of the Valves IIduring rotation of the assemblage and from a remote point or station.

The power or driving shaft 6 may be coupled to the engine of anautomobile or the like, in any suitable manner, and the driven shaft Iis rotatably supported in an antifriction bearing 25, which ispreferably a ball bearing of the sealed type as shown in Fig. 2. Thepump casing 8 is rigidly attached tothe driven shaft 1 by means of ahead flange 26, and the bored portion of the casing 8 is preferablyprovided with a series of external cooling fins 21 as clearly shown inFigs. 1 and 2. The intermediate frame section I2 is rigidly attached tothe pump casing 8 by means of bolts 28, and the other. frame section I3is rigidly attached to the section I2 by means of similar bolts 28. Thesame sides of the frame sections I2, I3 have a continuous openingtherein which is normally closed by a removable closure cover 29,removal of which effects unobstructed access to the interior of theframe. The end of the frame section I3 remote from the pump casing 8, isprovided with a bearing 30 within which the driving shaft 5 isrotatable, and the entire pump casing and frame assembly is preferablyformed of relatively small diameter sufi'icient only to permit housingof the movable elements therein. The Weight of the parts is alsopreferably reduced to a minimum, consistent with requisite strength, andthe driven shaft I may be connected to any device or apparatus which isto be propelled.

The bevel pinions 22, 23 which are secured to the crank shafts II, I8respectively, and which are adapted to be simultaneously rotated inopposite directions by the main driving gear 24, are preferably of likeand interchangeable construction, and the crank shafts II, I8 have theirinner ends independently journalled in a central bearing block 3|secured to the casing section I3. The cross-heads I5 have lateralguiding projections 32 which coact with the common guides I6, and aresimultaneously reciprocable along these guides but in oppositedirections. The piston rods I4 which are firmly secured to thecross-heads I5, are hollow and enter the cylinders through stuffingboxes 33; and the ends of the pistons Ill remote from the rods I4 areprovided with displacement rods 34 which slidably penetrate the headflange 26 through other stuffing-boxes 33. The valves II are preferablyof the butterfly type, being swingably supported on pivot pins 35, andare adapted to control the effective areas of the bypass openings formeddirectly within the correponding pistons I0. When these valves I I areset as indicated in Fig. 2, the displacement chambers within the bores 9on opposite sides of the pistons ID are in free and fully opencommunication with each other; and when the valves II are set as shownin Fig. 3, there is no communication whatever between the displacementchambers on the opposite sides of each piston Ill. The pistons II] arepreferably provided with snap rings 36 coacting with the bores 9 inorder to prevent leakage of liquid past the piston peripheries.

The by-pass valves I I are preferably adjustable to vary the effectivearea of the by-pass openings in the pistons II] from the exterior of thecasing 8 and from a remote station, and the mechanism for simultaneouslyeffecting similar adjustment of all of the valves II must be operablewhile the assemblage is revolving and without interfering with thegearing for reciprocating the pistons. This improved adjusting mechanismcomprises an actuating rod 31 slidably penetrating each piston rod I4and having its inner end operatively attached to an eccentric pin on thecorresponding valve II by means of a connection 38; crank arms 39swingably suspended from the cross-heads I5 and each having one armpivotally and slidably associated with the outer end of thecorresponding rod 3! and its other arm provided with a laterallyprojecting pin 40; a shifting bar 4| slidably mounted in the framesection I2 and cover 29 and having guides 42 rigidly attached theretoand coacting with the pins 48 so as to permit free reciprocation of thelatter with the pistons I0; a bell crank 43 pivotally attached to theexterior of the frame section I2 and havin one arm pivotally andslidably attached to an end of the shifting bar 4|; a rod 44 slidablymounted upon the frame section I3 and having one end pivotally attachedto the other arm of the bell crank 43, while its other end is adjustablyattached to a yoke 45; and a shifting collar 46 slidably butnon-rotatably supported by the driving shaft 6 and coacting with theyoke 45 so as to permit revolution of the latter with the frame sectionI3. The shifting bar 4! is prevented from rotating about its own axis bymeans of a guide pin 47, and the collar 46 is shiftable along the shaft6 by means of levers 48 carried by an actuating shaft 48 and coactingwith pins 58 on the collar. With this assemblage of elements, the shaft49 may be angularly adjusted to swing the levers 48 and to shift thecollar 46 at any time, and such shifting of the collar 46 will obviouslybe transmitted through the motion yoke 45, rod 44, bell-crank 43, bar Mand guides 42 to the several arms 39, rods 31, connections 38 and valvesI I so as to simultaneously shift these valves and. to retain them inshifted position.

The pump cylinders are normally completely filled with a liquid such asoil, and in order to permit such filling, I provide each bore 9 with aremovable plug 5I for permitting escape of confined air, and a checkvalve 52 is also provided on each cylinder. The oil is admissible underpressure through a pipe 53 communicating with the interior of afixedcasing 54, and the oil chamber within this casing 54 communicates withthe sealed bearing 25 and with a passage 55 formed in the driven shaftI. The passage 55 communicates through a pipe 56 with the inlet valve52, and after the pump chambers have been completely filled, the plugs5| must be inserted. The oil under pressure thereafter supplied to thepipe 53 will flow through the passage 55 and pipe 56 past the checkvalve 52 into the piston displacement chambers, in case of leakage, andwill always maintain these chambers completely filled withincompressible liquid, The interior of the frame sections I2, I3 arealso preferably supplied with grease for lubricating the mechanismconfined therein, and this grease and the oil within the pump structuresinsures ample lubrication of the entire assemblage at all times.

While the normal operation of my improved hydraulic transmissionmechanism should be apparent from the foregoing detailed description ofthe construction thereof, I shall give a short resume of this operation.When the displacement chambers of the bores 9 have been properlyinitially supplied with oil or other suitable liquid, and the plugs Ihave been inserted, and the chamber within the frame sections I2, I3 hasbeen supplied with grease and the closure cover 29 applied, the improvedmechanism is in condition for normal operation. Ihe driving shaft 6 maythen be operated at any desired speed from any suitable source of power.The by-pass valves Il may thereafter be adjusted to any desired positionby merely manipulating the levers 48, and when a particular position ofadjustment has been attained, the valves I I will remain in adjustedpcsition. If the valves I I are set as shown in Fig. 2, and the drivingshaft 6 is rotated, the rotation of this shaft 'will be imparted throughthe gear 24 to the pinionsZZ, 23 and from thence through the cranks I9,29, connecting rods 2|, cross-heads I5, and piston rods l4 to thepistons H3. Because the valves II are fully opened, the pistons It willmerely reciprocate within their bores 9 and the oil from one side of thepistons will merely pass therethrough to the other side withoutimparting motion to the casing 8 or the driven shaft 1. If the valveadjusting mechanism is thereafter manipulated so as to partially closethe valves ll, then the movement from one side of the pistons to theother will be retard-ed and this retardation of the oil flow willproportionately retard the movement of the pistons II]. This retardationof the pistons will impart revolving motion to the cylinder casing 8, inproportion to the degree of closing of the valves I I, and will causethe driven shaft I to revolve at a proportionately lower speed. If thevalves II are subsequently adjusted to closed position as shown in Fig.3, then the cylinder casing 8 will be revolved at the same speed as thatof the driving shaft 6 and the driven shaft 1 will rotate at like speed.It will thus be noted that any desired speed from zero to the maximumspeed to the driving shaft 6, may be imparted to the driven shaft 1, bymerely adjusting the positions of the butterfly valves I I.

From the foregoing detailed description it will be apparent that myinvention provides an extremely simple and compact hydraulictransmission which is readily adjustable to transfer motion from oneshaft to another at any desired speed. The power may obviously beapplied to either of the shafts 6, T. The valves I I are convenientlyadjustable while the shafts 6, T, casing B and frame sections I3, I4 arerevolving, and without interfering with movement of the pistons In bygearing associated with the driving shaft 6. The fins 21 associated withthe cylinder casing 8 will preventexcessive heating of the oil withinthe bores 9, and if the displacement chambers are constantly maintainedfilled with incompressible liquid, the transfer of motion will always beaccurate and uniform for a definite setting of the valves II. The entireassemblage has minimum diameter and weight, and therefor obviatesundesirable flywheel effect, and all portions of the assemblage areconveniently ascessible for inspection by merely removing the cover 29and by disconnecting the casing and frame elements. I have found that anassemblage of this kind must be perfectly balanced in order to avoidundesirable vibration during rotation thereof, and in my structure Ihave not only dynamically balanced the revolving mechanical elements,but I have also eliminated unbalanced conditions in the liquid body. Inthe improved assemblage, the liquid bodies in the cylinder bores aremaintained relatively fixed instead of being reciprocated, thusmaintaining the desired balanced condition at all times, and avoidingvibration. My improved hydraulic transmission has proven highlysatisfactory in actual use, especially in driving an automobile, .andcan obviously be manufactured and sold at relatively low cost ascompared to the present automobile transmission systems.

It should be understood that it is not desired to limit this inventionto the exact details of construction or to the precise mode ofoperation, herein shown and described, for various modifications withinthe scope of the claims may occur to persons skilled in the art.

I claim:--

1.A hydraulic transmission comprising, approximately alined driving anddriven shafts, a casing secured to one of said shafts and havingparallel cylinder bores extending toward the other shaft, a'singlepiston reciprocable within each of said cylinder bores and havinga'by-pass valve directly therein, and gearing interposed between saidpistons and said other shaft, said gearing being operable by said othershaft to reciprocat-e said pistons.

2. A hydraulic transmission comprising, approximately alined driving anddriven shafts, a

casing secured to one of said shafts and having parallel cylinder boresextending toward the other shaft, a single piston reciprocable withineach of said cylinder bores and having a by-pass valve directly therein,gearing interposed between said pistons and said other shaft, saidgearing being operable by said other shaft to reciprocate said pistons,and means operable from the exterior of said casing for changing thesetting of all of said valves.

3. A hydraulic transmission comprising, driving and driven shafts havingadjoining ends, a casing secured to the end of said driven shaft andhaving parallel cylinder bores extending toward said driving shaft end,a single piston reciprocable within each of said cylinder bores andhaving a by-pass opening therein, a butterfly valve carried by each ofsaid pistons for controlling the effective area of the by-pass opening,gearing operable by said driving shaft to reciprocate said pistons and aframe connecting said casing and said driving shaft and being journalledon the latter.

4. A hydraulic transmission comprising, driving and driven shafts havingadjoining ends, a casing secured to the end of said driven shaft andhaving parallel cylinder bores extending toward said driving shaft end,a single piston reciprocable within each of said cylinder bores andhaving a by-pass opening therein, a butterfly valve carried by each ofsaid pistons for controlling the effective area of the by-pass opening,gearing operable by said driving shaft to reciprocate said pistons, andmeans operable from the exterior of said casing for simultaneouslyadjusting all of said valves.

5. A hydraulic transmission comprising, driving and driven shafts, acasing assemblage secured to one of said shafts and journalled on theother and having parallel cylinder bores therein, a single pistonreciprocable within each of said bores, said pistons having by-passopenings therethrough, a valve carried by each of said pistons forcontrolling the by-pass opening thereof, hollow rods for reciprocatingsaid pistons, gearing operable by the other of said shafts for movingsaid pistons and said rods, and mechanism extending through said rodsfor effecting adjustment of said valves.

6. A hydraulic transmission comprising, driving and driven shafts, acasing assemblage secured to one of said shafts and journalled on theother and having parallel cylinder bores therein, a single pistonreciprocable within each of said bores, said pistons having by-passopenings therethrough, a valve carried by each of said pistons forcontrolling the by-pass opening thereof, hollow rods for reciprocatingsaid pistons, gearing operable by the other of said shafts for movingsaid pistons and said rods, and mechanism extending through said rodsfor effecting adjustment of said valves, said adjusting mechanism beingoperable from a stationary station externally of said casing.

7. A hydraulic transmission comprising, driving and driven shafts, acasing assemblage secured to one of said shafts and having parallelcylinder bores therein, a plurality of radiating fins associated withsaid casing around said bores, a piston reciprocable within each of saidbores and having a by-pass valve directly therein, and mechanism drivenby the other of said shafts for reciprocating said pistons.

8. A hydraulic transmission comprising, driving and driven shafts, acasing assemblage secured to one of said shafts and having parallelcylinder bores therein, a plurality of radiating fins associated withsaid casing around said bores, a piston reciprocable within each of saidbores and having a by-pass valve directly therein, mechanism driven bythe other of said shafts for reciprocating said pistons, and means forsimultaneously adjusting all of said valves from the exterior of saidcasing and through said piston actuating mechanism.

9. A hydraulic transmission comprising, driving and driven shafts, acasing assemblage rotatable with one of said shafts and having parallelcylinder bores therein, a piston reciprocable in each of said bores, aliquid by-pass valve carried directly by each of said pistons, means foradmitting liquid under pressure to each of said bores to constantly fillthe space around the piston therein, and means operable by the other ofsaid shafts for reciprocating said pistons.

10. A hydraulic transmission comprising, driving and driven shafts, acasing assemblage rotatable with one of said shafts and having parallelcylinder bores therein, a piston reciprocable in each of said bores, aliquid by-pass valve carried directly by each of said pistons, means foradmitting liquid under pressure to each of said bores to constantly fillthe space around the piston therein, and means operable by the other ofsaid shafts for reciprocating said pistons, and means for adjusting allof said valves from the exterior of said casing and while said shaftsare rotating.

BALDWIN BURHOP.

